Patrolling South Texas for Illegal Immigrants

"Yeah, 'cause they could be armed," Diaz tells him. A second ranch worker appears out of the brush, a middle-aged man with a long, gray beard. He says he was working near a dirt road when the Ford thundered past him, tearing through clumps of mesquite and cactus.

After a turn where the dirt road narrows, Diaz spots a cluster of flattened nopal cactus. "This is where he went through," he says. He turns the wheel, guns the engine and plows into the brush. We bounce along roughly for a moment and then lodge, stuck, in a thick tangle of mesquite that rises at least 2 feet over the grill of the 4x4. "Nope," he says. "Not gonna work." He throws the vehicle into reverse and soon we're back on the road and then easing into a clearing where several 4x4s and a canine unit gather.

The plane has spotted the truck in a nearby thicket. It appears to have been abandoned. Two agents start into the brush with M-4 rifles, followed by another agent leading a dog. The truck is in bad shape. The front left corner is caved in, the headlights cracked, and twigs and leaves protrude from every crevice. On the back cab window are Baylor and "Don't Mess With Texas" bumper stickers, and in the truck bed a black ski mask and a bottle of lotion.

The Ford turns out to be devoid of people and drugs. "They were probably aliens, then," says an agent named JJ. "Unless they took the bundles with them, and that's highly unlikely because it would weigh them down in the brush." Yet it's unusual for immigrants who have entered the country illegally to go to such lengths to avoid arrest. Most of the time, the guys who lead car chases through the brush are smugglers of some sort. Diaz guesses the men were scouts, paid to signal those transporting loads when the way is clear.

The chances of finding the men tonight look slim. Overhead, the sky is fading from glowing pink to dull, purplish blue. Diaz, somber and slightly frustrated, surveys two groups of agents that plan to comb the brush from opposite directions. "It's hard to follow sign here, with all the grass," he says. "But they'll meet in the middle. And if there's nothing, well, that's it."

Troy, the ranch hand, says he hasn't seen this type of thing before. Usually, immigrants walk through the ranch, sometimes asking for water or food. "I was at the gate one night and I heard, 'Amigo! Agua, por favor,'" he says. "It was two kids—couldn't have been more than 15. I gave them some water and chips." He looks out at the brush, the colors growing muted in the waning light.

"You gotta feel for them—it's 30 miles to the river," he says. "To walk 30 miles through this stuff for a better life? It's got to be bad."